Crystal structure and Hirshfeld surface analysis of 1-carb-oxy-2-(3,4-di-hydroxy-phen-yl)ethan-1-aminium chloride 2-ammonio-3-(3,4-di-hydroxy-phen-yl)propano-ate: a new polymorph of l-dopa HCl and isotypic with its bromide counterpart

Perumal Kathiravan; Thangavelu Balakrishnan; Perumal Venkatesan; Kandasamy Ramamurthi; María Judith Percino; Subbiah Thamotharan

doi:10.1107/S2056989016016789

Crystal structure and Hirshfeld surface analysis of 1-carb-oxy-2-(3,4-di-hydroxy-phen-yl)ethan-1-aminium chloride 2-ammonio-3-(3,4-di-hydroxy-phen-yl)propano-ate: a new polymorph of l-dopa HCl and isotypic with its bromide counterpart

Acta Crystallogr E Crystallogr Commun. 2016 Oct 25;72(Pt 11):1628-1632. doi: 10.1107/S2056989016016789. eCollection 2016 Nov 1.

Authors

Perumal Kathiravan¹, Thangavelu Balakrishnan¹, Perumal Venkatesan², Kandasamy Ramamurthi³, María Judith Percino², Subbiah Thamotharan⁴

Affiliations

¹ Crystal Growth Laboratory, PG and Research Department of Physics, Periyar EVR Government College (Autonomous), Tiruchirappalli 620 023, India.
² Laboratorio de Polímeros, Centro de Química Instituto de Ciencias, Benemérita Universidad Autónoma de Puebla (BUAP), Complejo de Ciencias, ICUAP, Edif. 103H, 22 Sur y San Claudio, CP 72570 Puebla, Puebla, Mexico.
³ Crystal Growth and Thin Film Laboratory, Department of Physics and Nanotechnology, SRM University, Kattankulathur 603 203, India.
⁴ Biomolecular Crystallography Laboratory, Department of Bioinformatics, School of Chemical and Biotechnology, SASTRA University, Thanjavur 613 401, India.

Abstract

The title mol-ecular salt, C₉H₁₂NO₄⁺·Cl^-·C₉H₁₁NO₄, is isotypic with that of the bromide counterpart [Kathiravan et al. (2016 ▸). Acta Cryst. E72, 1544-1548]. The title salt is a second monoclinic polymorph of the l-dopa HCl structure reported earlier in the monoclinic space group P2₁ [Jandacek & Earle (1971 ▸). Acta Cryst. B27, 841-845; Mostad & Rømming (1974 ▸). Acta Chemica Scand. B28, 1161-1168]. In the title compound, monoclinic space group I2, one of the dopa mol-ecules has a positive charge with a protonated α-amino group and the α-carb-oxy-lic acid group uncharged, while the second dopa mol-ecule has a neutral charge, the α-amino group is protonated and the α-carb-oxy-lic acid is deprotonated. In the previously reported form, a single dopa mol-ecule is observed in which the α-amino group is protonated and the α-carb-oxy-lic acid group is uncharged. The invariant and variations of various types of inter-molecular inter-actions present in these two forms of dopa HCl structures are discussed with the aid of two-dimensional fingerprint plots.

Keywords: Hirshfeld surfaces; crystal structure; cyclic N—H⋯Cl hydrogen bonds; l-dopa.